package com.example.chainsave.common.util;

import org.apache.commons.lang3.Validate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

/**
 * 以静态变量保存Spring ApplicationContext, 可在任何代码任何地方任何时候中取出ApplicaitonContext
 *
 * @author linyb1
 */
@Component
public class SpringContextHolder implements ApplicationContextAware, DisposableBean {

  private static ApplicationContext applicationContext = null;

  private static Logger logger = LoggerFactory.getLogger(SpringContextHolder.class);

  /**
   * 取得存储在静态变量中的ApplicationContext.
   */
  public static ApplicationContext getApplicationContext() {

    assertContextInjected();
    return applicationContext;
  }

  /**
   * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
   */
  @SuppressWarnings("unchecked")
  public static <T> T getBean(String name) {

    assertContextInjected();
    return (T) applicationContext.getBean(name);
  }

  /**
   * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
   */
  public static <T> T getBean(Class<T> requiredType) {

    assertContextInjected();
    return applicationContext.getBean(requiredType);
  }

  /**
   * 清除SpringContextHolder中的ApplicationContext为Null.
   */
  public static void clearHolder() {

    logger.debug("清除SpringContextHolder中的ApplicationContext:" + applicationContext);
    applicationContext = null;
  }

  /**
   * 实现ApplicationContextAware接口, 注入Context到静态变量中.
   */
  public void setApplicationContext(ApplicationContext applicationContext) {
    // logger.debug("注入ApplicationContext到SpringContextHolder:{}", applicationContext);

    if (SpringContextHolder.applicationContext != null) {
      logger.warn("SpringContextHolder中的ApplicationContext被覆盖, 原有ApplicationContext为:"
          + SpringContextHolder.applicationContext);
    }

    SpringContextHolder.applicationContext = applicationContext; // NOSONAR
  }

  /**
   * 实现DisposableBean接口, 在Context关闭时清理静态变量.
   */
  public void destroy() throws Exception {

    SpringContextHolder.clearHolder();
  }

  /**
   * 检查ApplicationContext不为空.
   */
  private static void assertContextInjected() {

    Validate.validState(applicationContext != null,
        "applicaitonContext属性未注入, 请在applicationContext.xml中定义SpringContextHolder.");
  }

}
